Comparison of the 2012 Seattle Energy Code with ASHRAE

Transcription

1 Comparison of the 2012 Seattle Energy Code with ASHRAE Final Report June 20, 2014 Prepared for the City of Seattle Office of Sustainability & Environment By Mike D. Kennedy, Inc.

2 Table of Contents 1 EXECUTIVE SUMMARY INTRODUCTION AND PURPOSE OF REPORT METHODOLOGY AND DATA SOURCES PRIMARY DATA SOURCES NEEA New Construction Survey Characteristics NPCC Sixth Plan and Floor Area Forecast PROTOTYPE BUILDINGS EVALUATED CODE DIFFERENCES ENERGY DIFFERENCE ESTIMATION Calculation Spreadsheet Simulations Engineering Method EFFICIENCY DIFFERENCE METRICS RESULTS BIBLIOGRAPHY APPENDIX A. MEASURE EVALUATION DETAILS A.1 ENVELOPE A.1.1 Envelope Insulation A.1.2 Maximum Glazing A.1.3 Air Barrier A.2 HVAC EFFICIENCY A.2.1 Limitation on Air Cooled Chiller Capacity A.2.2 Economizer A.2.3 Fractional HP Motors A.2.4 Demand Control Ventilation (DCV) A.2.5 Grocery Refrigeration HR A.2.6 Occupancy Controlled HVAC - Hotel / Motel A.2.7 Occupancy Controlled HVAC Classroom, Conference room, Gyms, and Auditoriums A.3 INTERIOR LIGHTING POWER ALLOWANCE A.4 LIGHTING CONTROLS A.4.1 Warehouse Occupancy Sensors A.4.2 Side Daylight Control A.4.3 Manual On or Automatic to 50% A.5 OTHER A.5.1 Classroom Occupancy Sensor (OS) Receptacles A.5.2 Energy Star Kitchen Equipment A.6 COMMISSIONING A.7 ADVANCED METERING A.8 RENEWABLES APPENDIX B. DIFFERENCES: 2012 SEATTLE ENERGY CODE TO ASHRAE Comparison of 2012 Seattle Energy Code and ASHRAE Commercial Building Provisions Page ii

3 List of Tables Table 1. Difference in Code Minimum Performance (( SEC ) / )... 4 Table 2. Evaluated Code Changes... 8 Table 3. Prototype Buildings Table 4. Seattle Commercial Sector by Prototype Type Table 5. Efficiency Difference Metrics Table 6. Difference in Code Minimum Efficiency All Measures Table 7. Difference in Code Minimum Efficiency Excluding Operations Measures Table 8. Envelope Data Summary (UA/ft 2 ). NEEA New Construction Survey Table 9. Primary Daylight Zone Side Daylight Calculation Assumptions Table 10. Secondary Daylight Zone Side Daylight Calculation Assumptions Table 11. Commissioning Requirements LIST OF FIGURES Figure 1. Portion of Energy Cost Savings by Code Provision Type... 5 Figure 2. Portion of Energy Cost Differential by Code Provision Type Figure 3. Portion of Total Site BTU Differential by Code Provision Type Figure 4. Portion of Electric Differential by Code Provision Type Figure 5. Portion of Gas Differential by Code Provision Type Comparison of 2012 Seattle Energy Code and ASHRAE Commercial Building Provisions Page iii

4 1 Executive Summary This report compares the commercial, non-residential provisions of the 2012 Seattle Energy Code (2012 SEC) with those of the ASHRAE Energy Standard for Buildings ( ). A qualitative comparison is made of all differences, and a quantitative estimate of the major differences is made. This evaluation is limited to the code prescriptive compliance paths. The City of Seattle adopted the 2012 SEC in November The code is an amended version of the 2012 Washington State Energy Code (2012 WSEC). In turn, the 2012 WSEC is a heavily amended version of the 2012 International Energy Conservation Code (2012 IECC). Both the state and city amendments are targeted at increasing code efficiency. A textual analysis identified 91 code differences with sixteen provisions judged more stringent than the 2012 SEC and seventy-one 2012 SEC provisions judged more stringent than The primary differences all favor the 2012 SEC over The 2012 SEC has: much higher minimum insulation requirements for all envelope components requires building air leakage testing and compliance with a maximum leakage of 0.4 CFM/ft 2 at 75PA requires full commissioning with plan, preliminary and final commissioning reports requires hourly metering of all energy sources and major end uses The quantitative estimate of the relative minimum efficiency level was made for 24 of the identified differences. The estimates were made using building energy simulation and engineering calculations on 14 building prototypes. Table 1 presents the difference in the 2012 SEC minimum performance relative to minimum performance. The 2012 SEC is more efficient than in all metrics in all building types. The commercial sector average result is determined from weighting the prototype savings by the projected new and addition floor area for the 10 year period 2015 through Table 1. Difference in Code Minimum Performance (( SEC ) / ) Percent 2012 SEC more efficient than Building Type Site Electric Site Gas Total Site Btu Energy Cost Regional Carbon 1 Grocery 3.9% 46.7% 17.3% 10.6% 11.8% Hospital 6.0% 13.9% 8.8% 7.5% 7.7% Lodging Hotel 8.7% 16.8% 11.5% 10.1% 10.4% Lodging Motel 9.8% 20.6% 11.7% 10.7% 10.8% Office Large 9.4% 29.1% 10.7% 9.9% 10.1% Office Medium 10.7% 24.4% 12.3% 11.4% 11.6% Office Small 5.9% 24.4% 8.1% 6.9% 7.1% Restaurant Sit Down 3.5% 49.1% 16.0% 9.6% 10.7% Restaurant Fast Food 2.1% 20.8% 8.7% 5.5% 6.1% Retail Large 5.6% 25.0% 10.7% 8.1% 8.5% Retail Small 1.9% 22.5% 9.2% 5.7% 6.3% School Primary 10.8% 31.3% 15.5% 13.0% 13.4% School Secondary 10.8% 49.8% 18.9% 14.6% 15.3% Warehouse 16.6% 30.8% 20.2% 18.3% 18.6% Weighted Average 8.2% 21.5% 11.3% 9.7% 10.0% 1- Assumes 0.8 lbs. /kwh (NPCC 2008) and 117 lbs. /therm (EIA) Comparison of 2012 Seattle Energy Code and ASHRAE Commercial Building Provisions Page 4

5 Figure 1 presents the contribution of each measure group to the energy cost savings. Envelope measures made up the largest block of savings, followed by advanced metering and commissioning. Figure 1. Portion of Energy Cost Savings by Code Provision Type 2 Introduction and Purpose of Report The City of Seattle has been a leader in the adoption of progressive commercial building energy codes. The City is in a unique position of being the electric energy provider as well as the enforcer of building codes. Over the last 34 years the City of Seattle has adopted energy codes above and beyond the Washington State code to increase minimum building energy efficiency, making it one of the nationwide leaders in commercial building energy efficiency. This report compares the prescriptive minimum performance levels of the 2012 SEC with and estimates energy impacts for the major differences. As with any work of this nature, there is significant uncertainty with the energy use difference estimates. By necessity, only the primary code differences those expected to have the largest impacts are evaluated in this work. Many other code provisions that differ between the codes have not been quantified due to limits in the available resources. Unevaluated differences are expected to have smaller impacts on minimum performance energy use but there are far more unevaluated items than evaluated items. Taken together these un-quantified provisions likely contribute significant additional savings, perhaps an additional 1-3%. As such, this work forms a conservative estimate of the 2012 SEC minimum performance energy use relative to Comparison of 2012 Seattle Energy Code and ASHRAE Commercial Building Provisions Page 5

6 3 Methodology and Data Sources This report estimates the change in minimum energy performance for moving from the to the 2012 SEC. The analysis method is designed to assess the impacts of the application of the code on typical northwest new construction and has been used by the Northwest Energy Efficiency Alliance and the Northwest Power and Conservation Council for more than 20 years to estimate regional energy savings potential from improvements in commercial building energy codes.. The process is as follows: Estimate the minimum performance requirements for the base code (e.g ) and the proposed code (e.g SEC) for each building in a sample of recently constructed buildings. The current evaluation utilizes a data set with detailed information on approximately 350 buildings. Summarize the minimum performance requirements of each building for key traits (e.g. heat loss rate, lighting power) by building type. Do this for both codes. Estimate energy use for code minimum performance of both codes in fourteen representative prototype buildings using energy simulation software and, where needed, engineering calculations. Compare the predicted energy performance of the codes. To get an average savings for all buildings in the Seattle commercial building sector, results from each of the fourteen individual building types are weighted based on the expected new construction / addition floor area forecasts from the Northwest Power and Conservation Council (NPCC) 6 th Power Plan 1 for Washington State adjusted to reflect the City of Seattle. It is important to note that the minimum performance difference here is a direct code-to-code comparison. Current practice in new construction energy efficiency is not accounted for. Current practice is generally better than code so that actual energy savings from a code change are diminished from the code-to-code comparison. Therefore, relative performance reported here reflects code stringency and is larger than the realized utility energy savings. There are two important areas not evaluated in this work. The code differences associated with remodel activity where triggers requiring code compliance differ between the codes, and, the impact of the code differences in midrise and high rise residential. These areas account for a very significant portion of the overall activity in the City of Seattle but are beyond the scope of this work. 3.1 Primary Data Sources NEEA New Construction Survey Characteristics The primary building characteristics data used in this work are derived from data collected as part of the Northwest Energy Efficiency Alliance (NEEA) Baseline Characteristics of the Non-Residential Sector study (Ecotope 2008) 2. This data was used to determine HVAC equipment type, performance, and associated minimum code performance, code maximum lighting power densities (LPD), code minimum building envelope characteristics, and average building geometry. The data is also used to determine the applicable of various code provision differences. For example, the percentage of cooling capacity required to have economizer in the 2012 SEC but not in is determined by looking at the size distribution of equipment found in the data base. The NEAA study buildings were built to the standards current during the 2001 code year. This data set is referred to as the NEEA Baseline. 1 Supporting data files from: Sixth Northwest Electric Power and Conservation Plan, Northwest Power and Conservation Council, Document Comparison of 2012 Seattle Energy Code and ASHRAE Commercial Building Provisions Page 6

7 3.1.2 NPCC Sixth Plan and Floor Area Forecast The Northwest Power and Conservation Council (NPCC) has developed several key regional information sources. The NPCC Sixth Power Plan evaluates energy savings and cost of a full range of electric energy conservation measures. Savings factors have been borrowed from this work. The NPCC also produces a regional floor area forecast. The most recent forecast is from September 2009 and estimates new nonresidential floor area to be built through 2029 by state and building type. This estimate is used to determine the overall new construction floor area in Washington State. The portion of state floor area occurring in the City of Seattle is determined for each building type from permit data. 3.2 Prototype Buildings Fourteen prototype buildings were used in this evaluation to represent Seattle s commercial building sector. The prototypes are based on building type descriptions that have been used in regional codes work for the Bonneville Power Administration and NEEA. The prototype descriptions capture the building geometry, envelope component types, operating schedules and set points, and HVAC system types and characteristics.. The prototype descriptions were adapted by the Bonneville Power Administration (Kennedy 2011) from US Department of Energy prototypes used by Pacific Northwest National Laboratory (PNNL) to evaluate ASHRAE (Halverson, 2011). The prototypes developed by PNNL were developed using the EnergyPlus building simulation software. The adaptation undertaken by BPA translated the descriptions to equest. The translations attempted to model the buildings as close to the PNNL approach as possible, though they are approximate in many aspects, as the programs have differing capabilities and approaches. Documentation of the prototype characteristics can be found at the PNNL repository for the 90.1 evaluation work. In particular, the score card spreadsheets are useful, though in some cases the actual PNNL models deviate from the published scorecard descriptions. 3.3 Evaluated Code Differences The first step was to identify all code differences between the 2012 SEC and In total, 91 differences were identified between the 2012 SEC and Sixteen of these are provisions where is judged to be the more stringent provision and 71 are provisions where the 2012 SEC is more stringent. Four differences were judged to be energy neutral. The differences were then prioritized by anticipated magnitude of energy impacts and then decisions made as to which differences should have energy impacts quantified. Table 2 presents the energy code differences that were quantitatively evaluated. A complete listing of energy code differences is presented in Appendix B with an indication of whether it has been evaluated and, if not, the reasoning for exclusion. This evaluation compares changes in the code prescriptive paths only. No attempt is made to compare performance paths, alternate compliance paths, or compliance tool (e.g. COMcheck) results. Comparison of 2012 Seattle Energy Code and ASHRAE Commercial Building Provisions Page 7

8 Table 2. Evaluated Code Changes Stronger Evaluated Provision Differences Evaluated Code Minimum Opaque Envelope Insulation SEC Yes Minimum Window Performance SEC Yes Air Leakage Testing and Minimum Leakage Rate SEC Yes Semi-heated Criteria and Insulation Requirements SEC Yes Limits on Air Cooled Chiller Capacity SEC Yes Economizer SEC Yes Fractional HP Motor efficiency SEC Yes Demand Control Ventilation Threshold SEC Yes Lighting Controls Automatic On 90.1 Yes OS Receptacles in Classrooms SEC Yes Lighting Controls Secondary Daylight Zone Control SEC Yes Commissioning SEC Yes On-site Renewables SEC Yes Grocery Heat Recovery SEC Yes Energy Metering (whole building and sub-metering) SEC Yes Energy Star Cooking Equipment SEC Yes Hotel/Motel HVAC Occupancy Control SEC Yes OS Control of Outside Air Damper or Local fan SEC Yes Key Provision Differences Exhaust Air Heat Recovery Thresholds SEC No Walk-in Cooler and Freezer requirements SEC No Optimum Start SEC No Measures evaluated include both physical energy saving attributes (e.g. envelope insulation, equipment efficiencies, or lighting controls) and operational measures (commissioning and advanced metering). The physical attributes create a base building with energy saving potential (e.g. low U-Value, equipment rated to operate at certain efficiencies, or lighting that is only on when needed) while the operational measures provide the means to ensure that the physical attributes operate as intended. The operational measures evaluated have been demonstrated to save energy over the life of the building. Northwest codes have included requirements for initial building commissioning for the last 10 years. Commissioning studies of new and existing buildings have reliably shown achieved energy savings through improved energy system operations (Mills, 2009). Advanced metering provides a means, short of continuous recommissioning, for discovery of operational problems. Both physical and operational measures are only effective if properly utilized and, from an energy saving point of view, operational improvements can be evaluated for projected savings similarly to equipment and control capabilities. A large number of identified code provision differences have not been evaluated in this work. A majority of the unevaluated differences are items where the 2012 SEC is more stringent that For a much smaller number of unevaluated items, is more stringent. These unevaluated items typically impact a limited number of buildings or system types. Individually they are not important, but taken together they represent additional savings not captured in these estimates. As a result this evaluation likely underestimates the performance of the 2012 SEC relative to Together these unevaluated items likely would add an additional savings of 1%-3%. Comparison of 2012 Seattle Energy Code and ASHRAE Commercial Building Provisions Page 8

9 3.4 Energy Difference Estimation The difference in energy use from code provision differences are estimated using building energy simulation supplemented with engineering calculations. Differential energy use estimates are made on a unit area basis for each building type. Average differential energy use across all building types are developed by combining the unit area savings estimates with the new construction/addition floor area forecasts from the Northwest Power and Conservation Council (NPCC) Sixth Power Plan 3 and factors apportioning total state floor area to the City of Seattle. The fourteen prototype buildings were modeled to determine differential energy use from changes in the primary performance variables (e.g., maximum lighting LPD, minimum equipment efficiency, and minimum envelope component efficiency). The simulations were also used to establish baseline energy use, which underlies all engineering estimates. The savings estimates made here are a direct code-to-code comparison. They do not account for better than code behavior of early adopters. For example, if 50% of the current buildings already incorporate a technology being evaluated, this fact is not considered. As a result, savings estimates reflect code stringency not actual utility energy savings. A more complete discussion of why code-to-code estimates do not reflect actual energy savings can be found in the 2011 NEEA Energy Code Evaluation (Kennedy, 2011, Appendix E). Details on the evaluated measures and individual savings calculations can be found in Appendix A and in the calculation spreadsheets Calculation Spreadsheet All energy use calculations are processed through a spreadsheet that combines simulation results, engineering calculations, applicability factors, and population estimates. The workbook contains a worksheet for each evaluated code difference, and worksheets to aggregate the energy use differentials. Unit area energy differentials for each code difference are calculated either through direct simulation or engineering calculations. Where measures are directly modeled, the calculation spreadsheets link to the simulation results, which are stored in a central simulation results spreadsheet. Where engineering calculations are used, the calculations are typically a function of simulation predicted end-use consumption. Energy differentials are calculated per square foot of applied measure and also per square foot of all floor area in the Seattle commercial sector for the building type. For the sector floor area estimate, the applied measure energy differential is adjusted for applicability of the code provision to the given building, heating fuel, system types, or other factors. The prototype building types and floor area forecast building types do not align perfectly. The worksheets include a crosswalk between the two building type systems. The savings calculations are done by prototype and then the savings are translated to the floor area forecast building types Simulations Simulations were conducted using the equest building energy simulation program and the prototype buildings described in 3.2. Table 3 lists the fourteen models utilized to represent the general building stock, along with their respective HVAC systems.. Table 4 presents the portion of the Seattle commercial building new construction represented by each prototype in terms or area, energy, and carbon. 3 Supporting data files from: Sixth Northwest Electric Power and Conservation Plan, Northwest Power and Conservation Council, Document 2008 Comparison of 2012 Seattle Energy Code and ASHRAE Commercial Building Provisions Page 9

10 Table 3. Prototype Buildings Building Type Baseline System/Fuel Grocery Package single-zone, gas heat Hospital VAV and CAV Standard non-fan powered terminals. Gas boiler, hot water reheat. Lodging Hotel Common areas: VAV; rooms: four pipe fan coils Lodging Motel Common areas: package single-zone, gas heat; rooms: PTAC Office Large VAV fan-less terminals. Gas boiler, hot water reheat. Office Medium VAV fan-less terminals. Gas furnace, electric reheat. Office Small Split system single-zone heat pump, gas auxiliary Restaurant Sit Down Package single-zone, gas heat Restaurant Fast Food Package single-zone, gas heat Retail Large Package single-zone, gas heat Retail Small Package single-zone, gas heat School Primary VAV fan-less terminals. Gas boiler, hot water reheat. Package single-zone with gas furnace for some common areas. School Secondary VAV fan-less terminals. Gas boiler, hot water reheat. Package single-zone with gas furnace for some common areas. Warehouse Package single-zone, gas heat. Unit heaters. Table 4. Seattle Commercial Sector by Prototype Type Avg. Annual Floor Area - 10 yr. Avg. Regional Carbon (lbs) Total Site Btu Site Elec Btu Site Gas Btu Grocery 0.6% 1.6% 1.5% 2.1% 1.6% Hospital 9.7% 29.0% 23.6% 44.0% 27.0% Lodging Hotel 1.9% 4.1% 3.3% 6.3% 3.8% Lodging Motel 1.0% 1.0% 1.0% 1.2% 1.0% Office Large 30.6% 18.3% 23.2% 4.5% 20.1% Office Medium 17.0% 11.8% 14.1% 5.2% 12.6% Office Small 6.4% 4.3% 5.1% 2.0% 4.6% Restaurant Sit Down 0.3% 2.0% 1.6% 3.1% 1.8% Restaurant Fast Food 0.3% 3.9% 2.6% 7.3% 3.4% Retail Large 2.2% 2.1% 2.1% 2.1% 2.1% Retail Small 1.5% 1.6% 1.4% 2.2% 1.6% School Primary 2.1% 2.2% 2.2% 2.4% 2.2% School Secondary 6.2% 5.2% 5.3% 4.8% 5.2% Warehouse 10.4% 3.0% 3.0% 2.9% 3.0% Other 10.0% 10.0% 10.0% 10.0% 10.0% Total 100.0% 100.0% 100.0% 100.0% 100.0% The base model characteristics for window-to-wall ratio for each prototype were updated based upon NEEA New Construction Survey data (See 3.1 Primary Data Sources). Code specific characteristics are also developed from the NEEA New Construction Survey buildings. The code characteristic (e.g. maximum LPD, minimum envelope heat loss, minimum cooling efficiency) for each building in the data set is estimated based upon the lighting area types, envelope component types, window area, and equipment types found in the building. The resulting code characteristics are averaged by building type (e.g. Comparison of 2012 Seattle Energy Code and ASHRAE Commercial Building Provisions Page 10

11 small office, large office, grocery). The prototype characteristics are then scaled so that the prototype averages match the NEEA Baseline averages. For example, code insulation requirements are assigned to each component in each building in the NEEA Baseline data, and the code whole building steady state heat loss rate is calculated. Adjustments are made to the code heat loss rate for NEEA Baseline buildings exceeding code maximum window-to-wall ratio (WWR) based upon the 2012 SEC component performance equations. These equations calculate the code steady-state heat loss rate using the building WWR or the code maximum WWR whichever is smaller. Buildings with high glazing fractions are assumed to maintain their high glazing fraction but improve insulation to compensate. This calculation is exactly analogous to the SEC Component Performance compliance path and very similar to the trade-offs allowed in 90.1 through COMcheck. The average code heat loss rate per unit floor area is calculated for each prototype building type (e.g. small office). The prototype component heat loss rates are then scaled so that the prototype heat loss rate per unit floor area is the same as the calculated average. This calculation is done for each code. A similar process is followed for window SHGC, lighting LPD, and cooling efficiency. Modeling the average characteristic derived from a large number of projects provides a truer assessment of the code impact than can be achieved by simply modeling the code prescriptive values in a specific prototype. The average for many buildings implicitly weights the various lighting area types, envelope component types, window area fractions, and equipment sizes so that the efficiency increase (or decrease) represents the sector response rather than that found for just the few situations represented in the models. All NEEA New Construction Survey buildings are used to set code characteristics no matter whether the building is actually located in Seattle. The use of all buildings allows much better characterization of a given building type, which has a critical impact on energy savings. Items such as the average office area within warehouse and the amount of CMU wall versus other wall types are better determined using a large number of points rather than the small number occurring in the data base within the City of Seattle. To the extent that Idaho buildings are built with different materials or a different mix of spaces, this treatment will introduce error. This trade-off was deemed worthwhile. Each prototype has a single heating fuel chosen to represent the most common fuel by building type. The final calculation spreadsheets calculate code differential use for buildings heated by electric, gas, and heat pumps from the default system consumption using simplified conversion factors. Average code differential energy use by building type is determined in the calculation spreadsheets by combining the consumption for each heating fuel case with the regional heating fuel type saturation found in the NEEA New Construction Survey data. Lost in this method is the impact of significant changes in system types or building configuration in the future. The world is seen through the lens of the audit data, which reflects the design choices of the past Engineering Method Measures such as motor control and lighting control improvements were evaluated using a simplified engineering approach. This approach was chosen when modeling was difficult within the confines of equest and the prototypes, or when modeling an average case was difficult and/or the model inputs would directly predict savings. For example, savings from a control strategy such as occupancy sensors are not modeled but are determined by applying a savings factor derived from field evaluations. Engineering calculations are implemented in the calculation spreadsheets. Generally, savings are calculated using engineering calculations based upon the predicted total energy use or predicted energy use for a specific end use, as determined from the prototype simulations. If applicable, engineering calculations utilize lighting measure interaction with HVAC factors developed from the simulations. As with the simulation results, the differential energy estimates are modified to account for heating fuel saturations and the applicability of the code language to given building or system type. To minimize double counting, end use consumption and interaction factors were taken from simulations that included the 2012 SEC LPD, UA, and HVAC performance improvements rather than the baseline models. Comparison of 2012 Seattle Energy Code and ASHRAE Commercial Building Provisions Page 11

12 3.5 Efficiency Difference Metrics Five metrics of efficiency have been generated in this work. All consider as the base code and the 2012 SEC as the proposed code. Each metric is the increase or decrease that results from the 2012 SEC relative to Positive numbers indicate increased performance by the SEC. Table 5. Efficiency Difference Metrics Metric Calculation Method / Notes Electric Use Calculated directly by the methods of Section 3.3. All thermal Gas Use consumption is assumed to be gas rather than oil or propane. Site Btu Gas Use (Btu) + Electric Use (kwh) / * 1000 Calculated assuming energy charges from general service rates only. Energy Cost PSE gas cost assumed to be $0.91/therm. SCL electric cost assumed to be $0.0764/kWh. Calculated using 11.7 lbs. of carbon per therm of natural gas (EIA) and 0.8 lbs. of carbon per kwh of electricity (NPCC 2008). The carbon Carbon associated with electricity assumes new electric use will contribute to regional marginal energy needs so uses an estimate of the average carbon content of the northwest marginal electric generation resources Comparison of 2012 Seattle Energy Code and ASHRAE Commercial Building Provisions Page 12

13 4 Results Comparing energy codes is a difficult exercise in language parsing and expected outcomes. Some things such as the LPD of office space might seem straightforward but when codes have alternate paths for lighting power it can be hard to determine what sort of impact a change in one path might make. Despite this uncertainty it is clear that the 2012 SEC meets or exceeds the requirements of in almost every aspect. Only a few provisions are weaker in the 2012 SEC and these for the most part are estimated to be of minor importance. There are many provisions where the 2012 SEC exceeds with a few responsible for a majority of the estimated energy savings and a multitude of provisions with smaller impacts. Table 6 presents the increase in building efficiency of the 2012 SEC over for the evaluated provisions. Gas efficiency gains are substantially larger than the others due to the large impact of envelope measures and the predominance of gas heating. The overall building consumption used to calculate the percentages in this table includes all modeled energy use including plug loads plus additional energy use associated with operational inefficiencies not captured by the models. The additional energy from operational inefficiency is estimated to be the full 3rd party commissioning savings potential as discussed for the commissioning measure in Appendix A. The actual efficiency increase due to the 2012 SEC would exceed these estimates if the impact of the many smaller provisions, most of which favor the 2012 SEC, were factored in. Table 6. Difference in Code Minimum Efficiency All Measures Percent 2012 SEC more efficient than (( SEC) / ) Building Type Site Electric Site Gas Total Site Btu Energy Cost Regional Carbon 1 Grocery 3.9% 46.7% 17.3% 10.6% 11.8% Hospital 6.0% 13.9% 8.8% 7.5% 7.7% Lodging Hotel 8.7% 16.8% 11.5% 10.1% 10.4% Lodging Motel 9.8% 20.6% 11.7% 10.7% 10.8% Office Large 9.4% 29.1% 10.7% 9.9% 10.1% Office Medium 10.7% 24.4% 12.3% 11.4% 11.6% Office Small 5.9% 24.4% 8.1% 6.9% 7.1% Restaurant Sit Down 3.5% 49.1% 16.0% 9.6% 10.7% Restaurant Fast Food 2.1% 20.8% 8.7% 5.5% 6.1% Retail Large 5.6% 25.0% 10.7% 8.1% 8.5% Retail Small 1.9% 22.5% 9.2% 5.7% 6.3% School Primary 10.8% 31.3% 15.5% 13.0% 13.4% School Secondary 10.8% 49.8% 18.9% 14.6% 15.3% Warehouse 16.6% 30.8% 20.2% 18.3% 18.6% Weighted Average 8.2% 21.5% 11.3% 9.7% 10.0% 1- Assumes 0.8 lbs. /kwh (NPCC 2008) and 117 lbs. /therm (EIA) Table 7 presents the increase in building efficiency of the 2012 SEC over excluding savings for commissioning and advanced metering. These are presented separately to facilitate comparison to LEED v4 where commissioning and whole building metering are prerequisites and advanced metering is a distinct credit, and therefore these operational savings are not considered in the energy savings calculations. The overall building consumption used to calculate the percentages in Table 7 differs from that used in Table 6 in that energy use associated with operational inefficiency is not included. Comparison of 2012 Seattle Energy Code and ASHRAE Commercial Building Provisions Page 13

14 Table 7. Difference in Code Minimum Efficiency Excluding Operations Measures Percent 2012 SEC more efficient than (( SEC) / ) Building Type Site Electric Site Gas Total Site Btu Energy Cost Regional Carbon 1 Grocery 0.4% 50.3% 14.2% 7.1% 8.4% Hospital 1.7% 9.6% 4.4% 3.1% 3.3% Lodging Hotel 3.4% 10.8% 5.7% 4.6% 4.8% Lodging Motel 5.6% 15.6% 7.2% 6.3% 6.4% Office Large 5.8% 30.2% 7.2% 6.4% 6.6% Office Medium 7.3% 24.2% 9.0% 8.0% 8.2% Office Small 5.0% 26.0% 7.3% 6.0% 6.2% Restaurant Sit Down 2.8% 53.8% 15.2% 8.7% 9.8% Restaurant Fast Food 1.5% 20.2% 7.4% 4.4% 5.0% Retail Large 1.0% 23.9% 6.5% 3.6% 4.1% Retail Small 0.7% 23.2% 8.0% 4.3% 5.0% School Primary 7.2% 31.9% 12.3% 9.6% 10.0% School Secondary 7.2% 54.8% 16.0% 11.2% 12.0% Warehouse 13.6% 32.1% 17.7% 15.5% 15.9% Weighted Average 4.8% 19.5% 7.8% 6.2% 6.5% 1- Assumes 0.8 lbs. /kwh (NPCC 2008) and 117 lbs. /therm (EIA) Figure 2 through Figure 5 attribute the efficiency improvement by code provision category as measured by energy cost, total site Btu, electricity, and natural gas. Envelope, commissioning, and metering provisions have the largest efficiency improvements and collectively account for 64% of the total improvement in energy cost. The envelope provisions of the 2012 SEC lead to a maximum envelope heat loss rates 20% lower than allowed by Every envelope component is required to have better thermal performance, with windows standing out as the most dramatic difference. The envelope portion of gas savings in Figure 5 is 40%. One area with no evaluated efficiency change is lighting power. There are several provision differences between the SEC and 90.1, some favoring SEC and one favoring However, because lighting power has two compliance options, and because of the general difficulty of determining the rate that the special allowances available in 90.1 can be utilized, no estimated savings are made. A complete discussion can be found in Appendix A. Comparison of 2012 Seattle Energy Code and ASHRAE Commercial Building Provisions Page 14

15 Figure 2. Portion of Energy Cost Differential by Code Provision Type Figure 3. Portion of Total Site BTU Differential by Code Provision Type Comparison of 2012 Seattle Energy Code and ASHRAE Commercial Building Provisions Page 15

16 Figure 4. Portion of Electric Differential by Code Provision Type Figure 5. Portion of Gas Differential by Code Provision Type Comparison of 2012 Seattle Energy Code and ASHRAE Commercial Building Provisions Page 16

17 5 Bibliography Baylon, D. and M. Kennedy Baseline Characteristics of the Non-Residential Sector: Idaho, Montana, Oregon, and Washington. Ecotope for the Northwest Energy Efficiency Alliance, Portland, OR. Baylon, David, Aaron Houseknecht, Jonathon Heller & Les Tumidaj Compliance with the 1994 Washington State Nonresidential Energy Code (NREC). Ecotope for the Utility Code Group. Baylon, D., M. Kennedy, and S. Borrelli Baseline Characteristics of the Non-Residential Sector in Idaho, Montana, Oregon, and Washington. Ecotope for the Northwest Energy Efficiency Alliance, Portland, OR. Bonneville Power Administration Room-based Occupancy Sensors M&V Grouse Mountain Lodge Whitefish, MT. Prepared by EMP2, Inc. Portland, OR. Bonneville Power Administration Packaged Terminal Heat Pumps and Room- Based Occupancy Sensors M&V Best Western Peppertree Airport Inn Spokane, WA Prepared by EMP2, Inc. Portland, OR. Emmerich, S.J., T. McDowell, and W. Anis Investigation of the Impact of Commercial Building Envelope Airtightness on HVAC Energy Use. June, Report No. NISTIR 7238, National Institute of Standards and Technology, Gaithersburg, Maryland Emmerich, Steven J. and Andrew K. Persily Airtightness of Commercial Buildings in the U.S. Building and Fire Research Laboratory, National Institute of Standards and Technology Gaithersburg, MD, USA EPA Occupancy Sensor Simulations and Energy Analysis for Commercial Buildings, Lighting Research Center Rensselaer Polytechnic Institute. FEMP Guidance for Electric Metering in Federal Buildings. U.S. Department of Energy, Washington, DC. DOE/EE FEMP Operations & Maintenance Best Practices. A Guide to Achieving Operational Efficiency. Release 3.0. U.S. Department of Energy. Washington, DC. Halverson, et. al ANSI/ASHRAE/IES Standard Final Determination Quantitative Analysis. Pacific Northwest National Laboratory. Richland, WA. Halverson, et. al ANSI/ASHRAE/IES Standard Preliminary Determination: Quantitative Analysis. Pacific Northwest National Laboratory. Richland, WA. M. Kennedy Non-Residential Energy Savings from Northwest Energy Code Changes For the Northwest Energy Efficiency Alliance, Portland, OR. M. Kennedy Analysis of Next-Generation Nonresidential Energy Codes in the Northwest. Bonneville Power Administration, Portland, OR. M. Kennedy Non-Residential Energy Savings from Northwest Energy Code Changes For the Northwest Energy Efficiency Alliance, Portland, OR. M. Kennedy Non-Residential Energy Savings from Northwest Energy Code Changes For the Northwest Energy Efficiency Alliance, Portland, OR. M. Kennedy Non-Residential Energy Savings from Northwest Energy Code Changes For the Northwest Energy Efficiency Alliance, Portland, OR. Kennedy, M. and D. Baylon Potential Energy Savings of Proposed Washington Non-Residential Energy Code. Ecotope, Seattle WA. Kennedy, M. and D. Baylon Survey of Energy Efficiency in Seattle s New Non-Residential Buildings: Ecotope for Seattle City Light, Seattle WA. Kennedy, M Comparison of Proposed Idaho and ASHRAE 90.1 Non-Residential Codes. For Battelle Pacific Northwest Laboratory, WA. Kennedy, Mike, J. Hanford, A. Houseknecht and D. Baylon Demand-Side Energy Savings in WNG Firm Commercial Sector. For Washington Natural Gas, Seattle, WA. Kennedy, M Energy Savings in Commercial Buildings: Impact of the Proposed 1995 Oregon State Energy Code. For the Northwest Power Planning Council, Portland, OR. Comparison of 2012 Seattle Energy Code and ASHRAE Commercial Building Provisions Page 17

18 Kennedy, M. and D. Baylon Energy Savings of Commercial Energy Code Compliance in Washington and Oregon. For the Washington State Energy Office, Olympia, WA. Mahone, D., C. Chappell, O. Howlett, D. Dohrmann, and F. Rubinstein. (to be published). Effectiveness of Bi- Level Switching in Offices, Retail Space and Classrooms. Heschong Mahone Group Inc. Fair Oaks, CA. Mills, Evan Building Commissioning: A Golden Opportunity for Reducing Energy Costs and Greenhouse Gas Emissions. Lawrence Berkeley National Laboratory for the California Energy Commission Public Interest Energy Research (PIER). Navigant Consulting, Inc Energy Savings Potential and RD&D Opportunities for Commercial Building Appliances. US DOE Office of Energy Efficiency and Renewable Energy Building Technologies Office. NPCC Marginal Carbon Dioxide Production Rates of the Northwest Power System. Northwest Power and Conservation Council. Portland, OR. Optimal Energy, Inc Documentation of the Northwest Energy Efficiency Alliance Efforts to Support Energy Codes and Participate in the Federal Standards Setting Process. Optimal Energy, Inc. Bristol VA. Plourde, Jim Making the Case for Energy Metering. ASHRAE Journal, Vol. 4, p US. DOE Guest Room HVAC Occupancy-Based Control Technology Demonstration. Prepared by PNNL. Zhang. J. et. al Energy Savings for Occupancy-Based Control (OBC) of Variable-Air-Volume (VAV) Systems. Pacific Northwest National Laboratory. Richland, WA. Comparison of 2012 Seattle Energy Code and ASHRAE Commercial Building Provisions Page 18

19 Appendix A. Measure Evaluation Details A.1 Envelope A.1.1 Envelope Insulation The 2012 SEC has more stringent minimum thermal integrity for all building envelope opaque and fenestration components. Savings from envelope code changes were estimated by simulating the regional prototypes. Prototype insulation levels were adjusted so the prototype heat loss rate per square foot corresponded to the estimated code heat loss rate per square foot. The code heat loss rate was derived from the respective prescriptive codes and the NEEA New Construction Survey data. For each of the 350 NEEA New Construction Survey buildings, a code heat loss rate was calculated for the 2012 SEC and by combining audit data with the respective code prescriptive minimum efficiency requirements. The whole building code heat loss rate per square foot of conditioned area was calculated for each code. Table 8 presents the resulting code heat loss rates for , the 2012 SEC, and the 2012 WSEC. Prototype insulation values of the modeled prototype were adjusted to achieve the target heat loss rates for each building type. Table 8. Envelope Data Summary (UA/ft 2 ). NEEA New Construction Survey Energy Code Code Heat loss Rate (UA/ft 2 ) SEC WA Zone 4c/5b Semi-heated insulation requirements were applied when the buildings complied with the respective code thresholds. Both the insulation requirements and thresholds are less stringent than the 2012 SEC. A.1.2 Maximum Glazing The 2012 SEC prescriptive code limits WWR to 30% of gross above-grade wall area, with two exceptions: The first allows a 40% WWR if more than 50% of the conditioned floor area is in a daylight zone. The second allows a 40% WWR if the fenestration U-values are approximately 10% better than required by the prescriptive code. This second option is allowed to serve as the baseline for a target UxA tradeoff calculation, but not for a Total Building Performance calculation. In calculating the 2012 SEC code heat loss rate, buildings that could achieved the 50% daylight zone threshold based upon the criteria below were assigned the lower code glazing performance values. For other buildings the SEC code values were calculated using the performance path equation with both sets of minimum requirements and associated WWR and the least stringent target adopted for the code heat loss. Determining the percent of buildings that could qualify for 50% daylight zone is difficult. The NEEA New Construction Survey data has poor information on this point. Assuming a 14' floorto-floor height, an optimally shaped building with a wall to floor ratio over 0.47 should be able to achieve 50% daylighting if they allow window head heights to rise to the maximum available Comparison of 2012 Seattle Energy Code and ASHRAE Commercial Building Provisions Page 19

20 height. This criteria was used to identify buildings that might achieve the 50% threshold in the NEEA Baseline data set. These candidates were then hand reviewed to determine whether the project could reasonably meet the threshold. Using this process a total of 3 buildings were determined to qualify for this exception A.1.3 Air Barrier The 2012 SEC code introduces explicit requirements for a building air barrier and requires all buildings to have an air leak test at 75 PA of less than 0.4 CFM/ft 2 of above-grade envelope. The building air barrier, materials and, assemblies are similar to those required by ASHRAE but 90.1 does not require testing. Quantification of the SEC savings due to requiring air leakage tests is complicated by two major uncertainties. First, baseline leakage rates are poorly understood with the primary leakage set being from the whole country and dominated by east coast, particularly buildings in Florida. The data set also has very few new buildings though the data that is present shows no diminishment of leakage in new buildings. Second, the performance of the building air barrier path without testing in is highly uncertain. The base building air leakage rate assumed in the savings evaluation of ASHRAE (Halverson 2011) was based upon building leakage data assembled by NIST (Emmerich et al. 2005). The data set characterizes leakage data on the basis of CFM per square foot of building surface area. The mean leakage rate of 1.8 cfm/ft 2 at 75 PA was used in the PNNL evaluation. Three extreme outliers in the data are responsible for moving the average from 1.0 cfm/ft 2 to 1.8 cfm/ft 2. The median is 1.0 cfm/ft 2. The 2005 NIST paper ( Airtightness of Commercial Buildings in the US by Emmerich and Persily) has a mean of 1.54 cfm/ft 2 of building surface area, (excluding floor), with higher levels in warehouse and lower in office for all climates. The paper also shows a strong correlation between air tightness and heating degree days, with much lower leakage rates in colder climates. The data has an average of 0.99 cfm/ft 2 for climates with >2000 degree days, with the caveat that they have little data for the western US. PNNL evaluated the air barrier language as part of the DOE Determination Quantitative Analysis (Halverson et. al. 2011). PNNL chose to use the mean value of the aforementioned data set (1.8 CFM/ft 2 ) as the baseline. They assumed that the 90.1 sealing language would reduce the infiltration 45% to 1.0 CFM/ft 2, and that a testing requirement would be needed to get lower. The basis for the assumption of the 45% reduction was based on direction from the 90.1 Envelope subcommittee rather than any analysis. All regional analysis (BPA 2012, NEEA 2011) has assumed a baseline leakage of 1.0 CFM/ft 2 of exterior surface as a more reasonable baseline for Pacific Northwest buildings. The 90.1 air barrier language might not reduce this leakage much in northern buildings and certainly PNNL assumes that air barrier language only gets the building to a leakage rate equal to the rate assumed as the base condition in this evaluation. We assume the 90.1 air barrier language reduces leakage 20% to 0.8 CFM/ft 2, a smaller percentage savings but leaving overall building leakage below what was assumed in the evaluation of This is conservative in that the lower baseline assumption combined with assuming some remaining savings from air barrier language means the air testing requirement of 2012 SEC will be assumed to reduce infiltration by a smaller amount (0.4 CFM/ft 2 ) compared with the 0.6 CFM/ft 2 increment implicit in the 90.1 evaluation. A.2 HVAC Efficiency A.2.1 Limitation on Air Cooled Chiller Capacity The 2012 SEC requires facilities with more than 500 tons of total chiller capacity and more than 100 tons of air cooled chiller capacity to have air cooled chillers 10% more efficient than code Comparison of 2012 Seattle Energy Code and ASHRAE Commercial Building Provisions Page 20

21 minimums for the capacity beyond 100 tons. The NEEA Baseline data indicates a small number of facilities will be required to improve chiller efficiency as a result. In applying the 2012 SEC equipment efficiency values to the NEEA Baseline buildings, those impacted by the above language were assumed to install more efficient air cooled chillers and the code efficiency values were adjusted for this factor. Simulation runs were done using the average code cooling efficiency and separately using the average 2012 SEC code efficiency. The difference reflects the average impact of this single provision. A.2.2 Economizer The economizer provisions of the 2012 SEC and are quite complicated and determining the applicability and impact of the differences involves separate treatment of different HVAC system types. In general, requires an air or water economizer but allows an unlimited quantity of equipment to be installed without an economizer as long as its cooling capacity is less than 54 kbtu/hr. The 2012 SEC requires air economizer and allows up to 72 kbtu/hr of cooling as long as the unit cool capacity is < 33 kbtu, or 54 kbtu for split system where the air handler is not adjacent to the exterior. For Group R the 2012 SEC has the same size limits but does not have a site limit on the total amount of cooling without economizer. In all cases the 2012 SEC economizer requirements are equivalent or more stringent than The economizer analysis was divided into distinct pieces. The Group R provisions impact lodging and high rise residential. Inspection of the NEEA Baseline hotel and motel buildings found that all buildings had equipment small enough to not require economizer in either the 2012 SEC or However, the 2012 SEC requires this equipment to be 15% more efficient. In this analysis, the lodging room cooling was modeled as 15% more efficient in the 2012 SEC runs. In addition, based upon NEEA Baseline data about 50% of room systems were heat pumps which are credited with heating savings as well. These savings are applied to all hotel and motel floor area. Single zone package equipment and fan coils were assumed to install economizer in all cases where 2012 SEC required economizer and did not. The impact of economizers was modeled in several building types. These savings were applied to the percentage of floor area served by systems less than 54kBtu excluding up to 72 kbtu of units smaller than 33kBtu. This percentage was estimated for each building type from the NEEA Baseline data. The 2012 SEC requires water source heat pump loops to have economizer except for up to 72 kbtu of units less than 33 kbtu, which covers nearly all water source heat pumps. Alternatively, there is a special exception that allows a 60% economizer if the equipment is 15% more efficient than the code tables exempts 76% of water source heat pumps based upon capacity. Buildings are assumed to utilize the SEC heat pump loop exemption which requires equipment to be 15% better rather than install an economizer. Savings are calculated as 15% of heating and cooling energy for all water source heat pumps with cooling capacity <=54 kbtu/hr. The heating and cooling energy for heat pumps is estimated using simple multipliers from each prototypes system energy use. The more efficient water source heat pumps will also be required to have partial airside economizer. In these systems, the economizer will save less than an economizer in other systems because reduced cooling from the economizer in the core of the building will be partially offset by decreased loop temperatures and a resulting increase in heating energy needs in the exterior zones. There will be additional savings from this partial economizer but they are suspected of being small and have not been quantified, as a heat pump loop system was not modeled. Comparison of 2012 Seattle Energy Code and ASHRAE Commercial Building Provisions Page 21